Lever escapement for a timepiece movement

ABSTRACT

The invention provides a compact and easily assembled lever escapement by making the lever from two pre-shaped flat parts fastened together. The first part has a lever notch and horns at one end, and notches on two arms at the other end. The second part has a guard pin or dart at one end and pallets carrying banking members at the other, the pallets being fitted into and located by the notches when the two parts of the lever are assembled. The construction enables a relatively small escapement wheel to be used, thus reducing its inertia and hence the wear on the pallets.

United States Patent [1 Jeanmairet et a1.

[ Nov. 5, 1974 [75] Inventors: Pierre Jeanmairet, Nidau; Andr Paroz, Brugg, both of Switzerland [73] Assignee: Marc Favre & Cie S.A., Canton of Berne, Switzerland 22 Filed: on. 4, 1973 [21] App]. No.: 403,658

[30] Foreign Application Priority Data [58] Field of Search 58/116 R, 116 M, 121 R, 58/121 A;29/177, 178

[5 6] References Cited UNITED STATES PATENTS 2,717,488 9/1955 Linard 58/121 R 3,248,783 5/1966 Tuetey 58/121 R X 3,708,975 1/1973 Davoine 58/121 R FOREIGN PATENTS OR APPLICATIONS 2,126,225 6/1972 France 58/121 R 93,041 7/1897 Germany 511/12] R 761,332 11/1956 Great Britain 58/121 R 243,142 6/1946 Switzerland 58/121 R Primary ExaminerGeorge H. Miller, Jr. Attorney, Agent, or Firm-1mirie and Smiley 5 7] ABSTRACT The invention provides a compact and easily assembled lever escapement by making the lever from two pre-shaped flat parts fastened together. The first part has a lever notch and horns at one end, and notches on two arms at the other end. The second part has a guard pin or dart at one end and pallets carrying banking members at the other, the pallets being fitted into and located by the notches when the two parts of the lever are assembled. The construction enables a relatively small escapement wheel to be used, thus reducing its inertia and hence the wear on the pallets.

7 Claims, 3 Drawing Figures sum ear 3 PATENTEBIUV 5 I874 LEVER ESCAPEMENT FOR A TIMEPIECE MOVEMENT BACKGROUND OF THE INVENTION The present invention has for its subject a lever escapement for a timepiece movement, the lever thereof being mounted to oscillate and provided with a dart and bankings.

The object of the present invention is to provide a lever escapement, which can be assembled mechanically and can cooperate with an escapement wheel having a reduced movement of inertia, and hence improved accuracy, i.e.,

a better ratio I/L4 Moment of inertia of the balance wheel/(Distance, wheel-balance) 4 This is because the invention enables the number of teeth on the escapement wheel to be reduced in number and hence the wheel can be reduced in size. Again, seeing that the oscillatory action of the lever is independent of the wheel movement, the manufacture of the latter is facilitated.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view an a large scale of an escapement mechanism according to the invention, taken along the line I-I of FIG. 2;

FIG. 2 is an enlarged section of the escapement mechanism of FIG. 1;

FIG. 3 is a plan view showing an alternative embodiment of the horns.

DETAILED DESCRIPTION OF THE INVENTION From FIGS. 1 and 2 it can be seen that the escapement comprises a lever 1 including a first portion constituted by an upper body 2 and a second portion constituted by a lower platform 3, which has an extension at the dart 4, which cooperates within the periphery of a safety-roller 5 to avoid an accidental upsetting of the lever l in the case of shocks.

The opposite end of the lower platform 3 comprises banking members 6, which at times come into contact with a ring 7 fashioned on a shoulder 8 of an escapement pinion 9, which is pivoted between a plate 10 and an escapement bridge 11.

The lever l is mounted on a shaft 14 also pivoted between the plate 10 and the escapement bridge 11.

The upper part 2 of the lever is provided at the two arm ends with notches l5, and serving to position semicircular pallets 16, which are fixed on the lateral faces of the banking members 6.

The shoulder 8 of the escapement pinion 9 carries an escapement wheel 18 having five teeth which considerably reduces its diameter compared with known escapement wheels. The wheel is driven by the pinion 9 of the gear train of the horological member in the usual manner.

The upper body 2 of the lever is notched at one of its ends to form a fork 20 presenting a lever notch 21 comprising horns 22, which co-operate with a peg 23 fixed in the roller 24 mounted on the balance staff 25 of the balance wheel.

The fork 20 is only shown in FIG. 1 and is machined in the upper body 2 only.

The upper body 2, after machining, is secured, as by soldering, riveting or by adhesive to the lower platform 3 The general principle of operation of the movement is known; in the embodiment, which forms the subject of the invention, the peg 23 engages temporarily in the notch 21 to initiate an oscillatory movement of the lever 1 around the shaft 14, which permits an unidirectional rotational rotation of the escapement wheel 18.

The oscillatory movements of the lever 1 in its two directions are limited by contact of the banking members 6 with the ring 7, which is located between the escapement wheel 18 and the pinion 9.

In an alternative embodiment (FIG. 3), the lower platform 3 of the lever l is provided with holes for positioning the pallets 16, the shape and dimension of these holes being determined by the profile of the pallets 16.

The escapement wheel 18 may be provided with a greater number of teeth if required, for example 15.

We claim:

1. A lever escapement for a time piece movement, comprising a lever mounted for oscillating motion and including a first and a second portion assembled together after forming thereof, said first portion having pallet guides and spaced horns defining a lever notch therebetween, said second portion including integrally a dart and banking members, and pallets on said banking members and engaged with said guides.

2. A lever escapement as recited in claim 1 including an escapement wheel and shaft and a disc fixed on said shaft so that said banking members strike alternatively against said disc.

3. An escapement as recited in claim 1, wherein said two lever portions are soldered together.

4. An escapement as recited in claim 1, wherein said two lever portions are secured together by an adhesive.

tion with respect to said first lever portion. 

1. A lever escapement for a time piece movement, comprising a lever mounted for oscillating motion and including a first and a second portion assembled together after forming thereof, said first portion having pallet guides and spaced horns defining a lever notch therebetween, said second portion including integrally a dart and banking members, and pallets on said banking members and engaged with said guides.
 2. A lever escapement as recited in claim 1 including an escapement wheel and shaft and a disc fixed on said shaft so that said banking members strike alternatively against said disc.
 3. An escapement as recited in claim 1, wherein said two lever portions are soldered together.
 4. An escapement as recited in claim 1, wherein said two lever portions are secured together by an adhesive.
 5. An escapement as recited in claim 1, wherein said two lever portions are riveted together.
 6. An escapement as recited in claim 1, wherein said escapement wheel has at least five teeth.
 7. An escapement as recited in claim 1, wherein said pallet guides on said first lever portion comprises open notches which during assembly of said first and second portions position said pallets on said second lever portion with respect to said first lever portion. 